add unfinished vertical box layout

src/VerticalBoxLayout.cpp

@@ -0,0 +1,28 @@
+#include "VerticalBoxLayout.hpp"
+#include "Point.hpp"
+#include "Widget.hpp"
+
+namespace Raven {
+
+void VerticalBoxLayout::run() {
+    if (!m_target) {
+        return;
+    }
+
+    Point current_point { m_target->rect().x() + m_margin, m_target->rect().y() + m_margin };
+    
+    auto& children = m_target->children();
+    for (auto child : children) {
+        if (child->absolute()) {
+            continue;
+        }
+
+        child->rect().set_x(current_point.x());
+        child->rect().set_y(current_point.y());
+
+        current_point.add(0, child->rect().height() + m_margin);
+    }
+}
+
+}
+

src/VerticalBoxLayout.hpp

@@ -0,0 +1,27 @@
+#pragma once
+
+#include "Layout.hpp"
+
+namespace Raven {
+
+class VerticalBoxLayout : public Layout {
+private:
+    double m_margin { 0.0 };
+public:
+    VerticalBoxLayout()
+        : Layout() {}
+
+    VerticalBoxLayout(double margin)
+        : Layout()
+        , m_margin(margin) {}
+
+    void run();
+
+    double margin() { return m_margin; }
+    void set_margin(double margin) { m_margin = margin; run(); }
+
+    virtual ~VerticalBoxLayout() {}
+};
+
+}
+